Integrated experimental and computational approach to analyse and design multiphase nanocomposites for broadband reflection loss

This study presents an integrated experimental and computational methodology for analysing multiphase composites with ceramic (BaTiO${}_3$, CoFe${}_2$O${}_4$) inclusions and carbon-based inclusions (MWCNTs) aimed at broadband electromagnetic (EM) reflection loss (RL) applications. Characterisation techniques (SEM, TGA, and X-ray 3-D tomography) were employed to analyse the nanocomposite. Fabricated nanocomposites were tested using a two-port VNA, and the EM properties of the composites were derived using the Nicolson-Ross-Weir (NRW) algorithm. An in-house optimisation tool is used to extract the EM properties of individual nanoparticles and later validate them using the experimental results. The RL spectrum in the frequency range is attained using the in-house Transfer Matrix Method (TMM)-based tool, which is validated using the scattering parameters obtained from the two-port VNA. Later, parametric studies are carried out using the validated in-house tools by varying the influencing parameters. Results have shown that composites with high BaTiO${}_3$ or MWCNT contents exhibited impedance mismatches, leading to immediate EM reflection upon interaction with the nanocomposite surface. In contrast, CoFe${}_2$O${}_4$-dominant composites achieved broadband RL ($<$ -10 dB) over a bandwidth of 4.4 GHz across different thicknesses even at higher loading due to improved impedance matching. Incident transverse magnetic (TM) polarised EM waves provided broadband RL up to 80° incidence. In contrast, transverse electric (TE) polarised EM waves showed broadband RL at angles up to 40° due to different field interactions. The proposed generalised approach offers a versatile framework for designing nanocomposites tailored for specific broadband or frequency-selective RL applications.